This invention relates to energy-saving fluorescent lamp systems and, more particularly, to a lamp system having a built-in protective device for preventing overcurrent current in the case a particular one of the two-lamp system fails to operate.
In recent years, substantial effort and development has been expended in reducing the energy consumed by existing fluorescent lamp systems. A number of devices have been disclosed for accomplishing this purpose. One such device is disclosed in U.S. Pat. No. 3,954,316, dated May 4, 1976, to Luchetta. This patent describes an attachment for inclusion in a two-lamp rapid-start fluorescent lamp circuit. It comprises an isolation transformer and a capacitor to reduce the electrical power consumption of the lamps. The capacitor is placed in series with the existing power factor correcting capacitor in the standard rapid-start ballast and this reduces the power consumption. The isolation transformer provides heater current for one of the electrodes in one of the lamps and also functions to improve power factor.
Another energy savings device is disclosed in U.S. Pat. No. 3,956,665, dated May 11, 1976 to Westphal. This patent discloses an energy saving device for replacing a fluorescent lamp in a two-lamp serially connected fluorescent fixture. This device permits the use of one of two lamps of a two-lamp system by substituting a capacitor for one of the lamps.
U.S. Pat. No. 4,082,981, dated Apr. 4, 1978 to Morton discloses an energy saving device for a rapid-start series-sequence type ballast for fluorescent lamps. The apparatus utilizes a switch in conjunction with a capacitor to limit the current supplied to the lamps after the lamps are initially energized. U.S. Pat. No. 4,163,176 dated July 31, 1979 to Cohen et al. discloses an instant-start fluorescent lamp and elongated extension base which houses a capacitance for reducing current flow through the lamp. U.S. Pat. No. 4,010,399, dated Mar. 1, 1977 to Bessone et al. discloses a switching circuit for a fluorescent lamp with heated filaments. The switching circuit can be held within one stem member cavity of the fluorescent lamp.